WO2023092599A1

WO2023092599A1 - Method, device and computer readable medium for communications

Info

Publication number: WO2023092599A1
Application number: PCT/CN2021/134156
Authority: WO
Inventors: Gang Wang; Zhaobang MIAO
Original assignee: Nec Corporation
Priority date: 2021-11-29
Filing date: 2021-11-29
Publication date: 2023-06-01

Abstract

Embodiments of the present disclosure relate to method, device and computer readable media for communications. A method comprises determining, at a terminal device, at least one factor for sidelink communication; and determining a first set of candidate resources by excluding a reserved resource from an initial set of candidate resources based on the at least one factor. The at least one factor comprises at least one of the following: a first factor associated with a first type of resource reserved with period, a second factor associated with a second type of resource reserved with time offset, a third factor associated with a first threshold of Reference Signal Receiving Power (RSRP), or a fourth factor associated with the first threshold.

Description

METHOD, DEVICE AND COMPUTER READABLE MEDIUM FOR COMMUNICATIONS

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication, and in particular, to a method, device and computer readable media for sidelink communication.

BACKGROUND

Sidelink in unlicensed spectrum or band (SL-U) is a key topic in Release 18 of the 3rd Generation Partnership Project (3GPP) . SL-U should base on New Radio (NR) sidelink and NR-U. Mode 2 resource sensing and selection procedure in Release 16 is based on a sidelink dedicated resource pool. For SL-U, no dedicated resource pools can be configured for sidelink. Thus, the mode 2 resource sensing and selection procedure should be modified accordingly.

SUMMARY

In general, example embodiments of the present disclosure provide methods, devices and computer readable media for communications.

In a first aspect, there is provided a method for communications. The method comprises: determining, at a terminal device, at least one factor for sidelink communication; and determining a first set of candidate resources by excluding a reserved resource from an initial set of candidate resources based on the at least one factor. The at least one factor comprises at least one of the following: a first factor associated with a first type of resource reserved with period, a second factor associated with a second type of resource reserved with time offset, a third factor associated with a first threshold of Reference Signal Receiving Power (RSRP) , or a fourth factor associated with the first threshold.

In a second aspect, there is provided a terminal device. The terminal device comprises a processor and a memory storing instructions. The memory and the instructions are configured, with the processor, to cause the terminal device to perform the method according to the first aspect.

In a third aspect, there is provided a computer readable medium having instructions stored thereon. The instructions, when executed on at least one processor of a device, cause the device to perform the method according to the first aspect.

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

Fig. 1 illustrates an example communication network in which implementations of the present disclosure can be implemented;

Fig. 2 illustrates an example of automatic gain control (AGC) symbol and guard period (GP) symbol in accordance with some embodiments of the present disclosure;

Fig. 3 illustrates an example of a sub-channel in accordance with some embodiments of the present disclosure;

Fig. 4 illustrates an example of CO sharing in accordance with some embodiments of the present disclosure;

Fig. 5 illustrates an example of a sensing window and a selection window in a sensing and resource selection procedure;

Fig. 6 illustrates a flowchart of a legacy mode 2 sensing and resource selection procedure;

Fig. 7 illustrates a flowchart of an example method in accordance with some embodiments of the present disclosure;

Figs. 8A, 8B, 8C and 8D illustrate a flowchart of an example method in accordance with some embodiments of the present disclosure, respectively;

Fig. 9 illustrates an example of a sensing duration of the last type 1 CA procedure in accordance with some embodiments of the present disclosure;

Figs. 10 and 11 illustrate a flowchart of an example method in accordance with some embodiments of the present disclosure, respectively; and

Fig. 12 is a simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitations as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As used herein, the term ‘terminal device’ refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE) , personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs) , portable computers, tablets, wearable devices, internet of things (IoT) devices, Ultra-reliable and Low Latency Communications (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, device on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, devices for Integrated Access and Backhaul (IAB) , Space borne vehicles or Air borne vehicles in Non-terrestrial networks (NTN) including Satellites and High Altitude Platforms (HAPs) encompassing Unmanned Aircraft Systems (UAS) , eXtended Reality (XR) devices including different types of realities such as Augmented Reality (AR) , Mixed Reality (MR) and Virtual Reality (VR) , the unmanned aerial vehicle (UAV) commonly known as a drone which is an aircraft without any human pilot, devices on high speed train (HST) , or image capture devices such as digital cameras, sensors, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. The ‘terminal device’ can further has ‘multicast/broadcast’ feature, to support public safety and mission critical, V2X applications, transparent IPv4/IPv6 multicast delivery, IPTV, smart TV, radio services, software delivery over wireless, group communications and IoT applications. It may also incorporated one or multiple Subscriber Identity Module (SIM) as known as Multi-SIM. The term “terminal device” can be used interchangeably with a UE, a mobile station, a subscriber station, a mobile terminal, a user terminal or a wireless device.

The term “network device” refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a Node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a next generation NodeB (gNB) , a transmission reception point (TRP) , a remote radio unit (RRU) , a radio head (RH) , a remote radio head (RRH) , an IAB node, a low power node such as a femto node, a pico node, a reconfigurable intelligent surface (RIS) , and the like.

The terminal device or the network device may have Artificial intelligence (AI) or Machine learning capability. It generally includes a model which has been trained from numerous collected data for a specific function, and can be used to predict some information.

The terminal or the network device may work on several frequency ranges, e.g. FR1 (410 MHz –7125 MHz) , FR2 (24.25GHz to 71GHz) , frequency band larger than 100GHz as well as Tera Hertz (THz) . It can further work on licensed/unlicensed/shared spectrum. The terminal device may have more than one connection with the network devices under Multi-Radio Dual Connectivity (MR-DC) application scenario. The terminal device or the network device can work on full duplex, flexible duplex and cross division duplex modes.

The embodiments of the present disclosure may be performed in test equipment, e.g. signal generator, signal analyzer, spectrum analyzer, network analyzer, test terminal device, test network device, channel emulator

As used herein, the singular forms ‘a’ , ‘an’ and ‘the’ are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term ‘includes’ and its variants are to be read as open terms that mean ‘includes, but is not limited to. ’ The term ‘based on’ is to be read as ‘at least in part based on. ’ The term ‘some embodiments’ and ‘an embodiment’ are to be read as ‘at least some embodiments. ’ The term ‘another embodiment’ is to be read as ‘at least one other embodiment. ’ The terms ‘first, ’ ‘second, ’ and the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below.

In some examples, values, procedures, or apparatus are referred to as ‘best, ’ ‘lowest, ’ ‘highest, ’ ‘minimum, ’ ‘maximum, ’ or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

Fig. 1 illustrates a schematic diagram of an example communication network 100 in which embodiments of the present disclosure can be implemented. As shown in Fig. 1, the communication network 100 may include a terminal device 110, a terminal device 120, a terminal device 130,

network devices

140 and 150. The

network devices

140 and 150 may communicate with the terminal device 110, the terminal device 120 and the terminal device 130 via respective wireless communication channels.

In some embodiments, the network device 140 may be a gNB in NR, and the network device 150 may be an eNB in Long Term Evolution (LTE) system.

It is to be understood that the number of devices in Fig. 1 is given for the purpose of illustration without suggesting any limitations to the present disclosure. The communication network 100 may include any suitable number of network devices and/or terminal devices adapted for implementing implementations of the present disclosure.

The communications in the communication network 100 may conform to any suitable standards including, but not limited to, Global System for Mobile Communications (GSM) , LTE, LTE-Evolution, LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , GSM EDGE Radio Access Network (GERAN) , Machine Type Communication (MTC) and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols.

In some embodiments, the communications in the communication network 100 may comprise sidelink communication. Sidelink communication is a wireless radio communication directly between two or more terminal devices, such as two or more terminal devices among the terminal device 110, the terminal device 120 and the terminal device 130. In this type of communication, the two or more terminal devices that are geographically proximate to each other can directly communicate without going through the

network device

140 or 150 or through a core network. Data transmission in sidelink communication is thus different from typical cellular network communications, in which a terminal device transmits data to the network device 140 or 150 (i.e., uplink transmissions) or receives data from the network device 140 or 150 (i.e., downlink transmissions) . In sidelink communication, data is transmitted directly from a source terminal device (such as the terminal device 110) to a target terminal device (such as the terminal device 120) through the Unified Air Interface, e.g., PC5 interface, (i.e., sidelink transmissions) , as shown in Fig. 1.

Sidelink communication can provide several advantages, including reducing data transmission load on a core network, system resource consumption, transmission power consumption, and network operation costs, saving wireless spectrum resources, and increasing spectrum efficiency of a cellular wireless communication system.

In a sidelink communication system, the sidelink resource is used to transmit information between terminal devices. According to application scenarios, service types, etc., a sidelink communication manner includes but is not limited to device to device (D2D) communication, Vehicle-to-Everything (V2X) communication, etc.

V2X communication enables vehicles to communicate with other vehicles (i.e. Vehicle-to-Vehicle (V2V) communication) , with infrastructure (i.e. Vehicle-to-Infrastructure (V2I) , with wireless networks (i.e. Vehicle-to-Network (V2N) communication) , with pedestrians (i.e. Vehicle-to-Pedestrian (V2P) communication) , and even with the owner's home (i.e. Vehicle-to-Home (V2H) ) . Examples of infrastructure include roadside units such as traffic lights, toll gates and the like. V2X communication can be used in a wide range of scenarios, including in accident prevention and safety, convenience, traffic efficiency and clean driving, and ultimately in relation to autonomous or self-driving vehicles.

For sidelink communications, a terminal device uses resources in sidelink resource pools to transmit or receive signals. The sidelink resource pools include resources in time domain and frequency domain, which are dedicated resources of the sidelink communication, or shared by the sidelink communication and a cellular link.

In a sidelink resource pool which may contain multiple slots and resource blocks (RBs) , and all or part of the symbols in a slot can be used for sidelink transmission. Within a resource pool, among all the symbols configured for sidelink in each slot, the first symbol (i.e., the start symbol) is used as the automatic gain control (AGC) symbol, and the last symbol used as a guard period (GP) symbol. AGC symbols and GP symbols can be considered as fixed overheads in sidelink resource. In the description of the following embodiments, AGC symbols and GP symbols are included in the sidelink symbols which are indicated by the sidelink channel resource configuration, and AGC symbols carry redundancy sidelink information while GP symbols are not used for carrying sidelink information, as shown in Fig. 2.

The terminal device 110, the terminal device 120 and the terminal device 130 may use sidelink channels to transmit sidelink signaling or information. The sidelink channels include at least one of the following: a Physical Sidelink Control Channel (PSCCH) resource which is used for carrying sidelink control information (SCI) , a Physical Sidelink Shared Channel (PSSCH) resource which is used for carrying sidelink data service information, a physical sidelink feedback channel (PSFCH) resource which is used for carrying sidelink ACK/NACK feedback information, a physical sidelink broadcast channel (PSBCH) resource which is used for carrying sidelink broadcast information, and a physical sidelink discovery channel (PSDCH) resource which is used for carrying a sidelink discovery signal.

Within a resource pool, a PSSCH resource includes all the symbols in a slot that are configured as sidelink available symbols, and one or more sub-channels in frequency domain, where each sub-channel contains an integer number of consecutive RBs. The number m of RBs included in one sub-channel is also called the sub-channel size. Each slot contained in the resource pool contains multiple available sidelink symbols, and the PSSCH resource is located in the time domain from the first available sidelink symbol in this slot to all available symbols. In the frequency domain, the resource pool contains multiple RBs, according to the sub-channel size m, starting from the first RB in the resource pool, each m RBs are divided into one sub-channel, and each PSSCH channel resource is located on one or more sub-channels. When one of the terminal device 110, the terminal device 120 and the terminal device 130 uses the PSSCH resource to send sidelink information, it can use one or more sub-channels to carry corresponding data information. A PSCCH resource includes t symbols in time domain, and k RBs in frequency domain. Each PSCCH channel resource is located at consecutive t symbols starting from the first symbol in the available symbols in the time domain, and located at the position of consecutive k RBs starting from the first RB in the corresponding sub-channel in the frequency domain, as shown in Fig. 3.

In NR-U schemes, the network device 140 or one of

terminal device

110, 120 and 130 may access to a channel in unlicensed spectrum by using a channel access procedure, and obtain a Channel Occupancy (CO) . A Channel Occupancy Time (COT) refers to total time for a CO which may be shared between the network device 140 and one of

terminal device

110, 120 and 130, as shown in Fig. 4.

A terminal device may select resources from its transmission resource pool for sidelink signal transmission by using a sensing and resource selection procedure. Fig. 5 illustrates an example of a sensing window and a selection window in a sensing and resource selection procedure. As shown, a sensing and resource selection procedure is triggered in slot #n. During the procedure, the terminal device senses resources within a sensing window 510 in a resource pool and try to decode SCI in configured PSCCH resources. Then, based on the measurement results and control information obtained from the SCI, the terminal device may further determine a candidate resource set within a selection window 520 and report the set to high layer of the terminal device.

Fig. 6 illustrates a flowchart of a legacy mode 2 sensing and resource selection procedure 600. Hereinafter, the legacy mode 2 sensing and resource selection procedure will be referred to as “legacy mode 2 procedure” for short.

As shown, at block 610, the terminal device sets candidate resources R _x, y in the selection window [n+T1, n+T2] .

At block 615, the terminal device sets the sensing window [n-T0, n-T _pro. 0] .

At block 620, the terminal device sets a Reference Signal Receiving Power (RSRP) threshold list.

At block 625, the terminal device initializes the initial set S _A to the set of all the candidate resources R _x, y.

At block 630, the terminal device excludes, from the initial set S _A, resources related to slots that are not sensed by the terminal device.

At block 635, the terminal device determines whether the number of candidate resources R _x, y remaining in the set S _A is smaller than X·M _total, where X represents a percentage which may be configured or pre-configured, and M _total represents the total number of candidate single-slot resources.

If the number of candidate resources R _x, y remaining in the set S _A is smaller than X·M _total, at block 640, the terminal device initializes the set S _A to the initial set of all the candidate resources R _x, y as at block 625, and go to block 645.

If the number of candidate resources R _x, y remaining in the set S _A is not smaller than X·M _total, the terminal device, at block 645, excludes a resource from the set S _A, if all the following conditions at

block

645A, 645B and 645C are met.

At block 645A, the terminal device derives values of prio _RX and P _{rsvp_RX} from the SCI, where prio _RX represents a priority of signals received by the terminal device, and P _{rsvp_RX} represents a resource reservation period.

At block 645B, the terminal device determines that the RSRP measurement is higher than a RSRP threshold Th (prio _RX, prio _TX) in the RSRP threshold list, where prio _TX represents a priority of signals to be transmitted by the terminal device. The terminal device may determines the RSRP threshold Th (prio _RX, prio _TX) based on prio _RX and prio _TX.

At block 645C, the terminal device determines that a reserved resource of other terminal device overlaps with a candidate resource in the set S _A.

At block 650, the terminal device determines whether the number of candidate resources R _x, y remaining in the set S _A is smaller than X·M _total as at block 650.

If the number of candidate resources R _x, y remaining in the set S _A is not smaller than X·M _total, the terminal device, at block 655, determines a candidate resource set for sidelink communication.

If the number of candidate resources R _x, y remaining in the set S _A is smaller than X·M _total, the terminal device, at block 660, increases all the RSRP thresholds in the RSRP threshold list by 3dB. Then, the procedure 600 returns to block 625.

In view of the above, the legacy mode 2 procedure is used for determining the candidate resources set for further sidelink transmission by a terminal device. The candidate resources are selected based on measurement results and SCI decoding in a sidelink resource pool which is a dedicated resource set for sidelink and no other types of nodes can use. In other words, the resource reservation information obtained from SCI is “clear and certain” in the legacy mode 2 procedure. But for SL-U, similar information may be dubious since the reserved resources may not be used while the relevant channel access procedure fails.

If the legacy mode 2 procedure is reused in SL-U directly, the resources excluded from the initial resource set based on SCI decoding may be wasted, and less or even no candidate resources may be selected. Therefore, some modifications of the legacy mode 2 procedure should be considered for SL-U to improve the sidelink resource selection performance.

Embodiments of the present disclosure provide a solution for sidelink transmission so as to solve the above problems and one or more of other potential problems. The solution uses additional factors that may impact whether a resource should be excluded from an initial resource set or not. In this way, more candidate resources may be provided to high layer for sidelink transmission in SL-U.

Fig. 7 illustrates a flowchart of an example method 700 in accordance with some embodiments of the present disclosure. In some embodiments, the method 700 can be implemented at a terminal device, such as one of the terminal device 110, the terminal device 120 and the terminal device 130 as shown in Fig. 1. For the purpose of discussion, the method 700 will be described with reference to Fig. 1 as performed by the terminal device 110 without loss of generality.

At block 710, the terminal device 110 determines at least one factor for sidelink communication. At block 720, the terminal device 110 determines a first set of candidate resources by excluding a reserved resource from an initial set of candidate resources based on the at least one factor. The at least one factor comprises at least one of the following: a first factor associated with a first type of resource reserved with period, a second factor associated with a second type of resource reserved with time offset, a third factor associated with a first threshold of RSRP, or a fourth factor associated with the first threshold.

With the at least one factor being introduced, the probability of excluding candidate resources in the legacy mode 2 procedure may be modified. Thus, more candidate resources may be provided to high layer for sidelink transmission in SL-U.

In some embodiments, upon determining the first set of candidate resources, the terminal device 110 may report the first set of candidate resources to high layer of the terminal device 110. For example, a physical layer of the terminal device 110 may report the first set of candidate resources to the high layer of the terminal device 110.

In some embodiments, the terminal device 110 may exclude the first type of resource from the initial set of candidate resources by a first probability. The first probability may be determined based on the first factor. This will be described with reference to Fig. 8A.

Fig. 8A illustrates a flowchart of an example method 800A in accordance with some embodiments of the present disclosure. The method 800A may be considered as an example implementation of the method 700. In some embodiments, the method 800A can be implemented at a terminal device, such as one of the terminal device 110, the terminal device 120 and the terminal device 130 as shown in Fig. 1. For the purpose of discussion, the method 800A will be described with reference to Fig. 1 as performed by the terminal device 110 without loss of generality.

At block 810, the terminal device 110 determines the first factor.

At block 815, the terminal device 110 identifies the first type of resource reserved with period. For example, the first type of resource may be reserved for periodic service.

In some embodiments, similar to the action at block 625 in Fig. 6, the terminal device 110 may initialize an initial set of candidate resources to the set of all the candidate resources R _x, y.

At block 820, the terminal device 110 excludes the first type of resource from the initial set of candidate resources by a first probability. The first probability is determined based on the first factor. The first probability may be represented by α and 0≤α≤1.

At block 825, the terminal device 110 determines the first set of candidate resources.

It will be understood that the probability of excluding the resource in the legacy mode 2 procedure is 100%. For example, the probability of excluding the resource at

blocks

630 and 645 in Fig. 6 is 100%. However, the probability of excluding the first type of resource at block 820 may be lower than 100%. It means that less resources may be excluded from the initial set of candidate resources. Thus, more candidate resources may be provided to high layer for sidelink transmission.

It shall be appreciated that, although presented herein as being performed serially, at least a portion of the actions of the method 800A may be performed contemporaneously or in a different order than as presented in Fig. 8A. For example, the action at block 810 may be performed after the action at block 815. Alternatively, the actions at

blocks

810 and 815 may be performed contemporaneously. The scope of the present disclosure is not limited in this regard.

In some embodiments, the terminal device 110 may exclude the second type of resource from the initial set of candidate resources by a second probability. The second probability may be determined based on the second factor. This will be described with reference to Fig. 8B.

Fig. 8B illustrates a flowchart of an example method 800B in accordance with some embodiments of the present disclosure. The method 800B may be considered as an example implementation of the method 700. In some embodiments, the method 800B can be implemented at a terminal device, such as one of the terminal device 110, the terminal device 120 and the terminal device 130 as shown in Fig. 1. For the purpose of discussion, the method 800B will be described with reference to Fig. 1 as performed by the terminal device 110 without loss of generality.

At block 830, the terminal device 110 determines the second factor.

At block 835, the terminal device 110 identifies the second type of resource reserved with time offset. For example, the second type of resource may be reserved for sidelink retransmission.

At block 840, the terminal device 110 excludes the second type of resource from the initial set of candidate resources by a second probability. The second probability is determined based on the second factor. The second probability may be represented by β and 0≤β≤1.

At block 845, the terminal device 110 determines the first set of candidate resources.

It will be understood that the probability of excluding the resource in the legacy mode 2 procedure is 100%. However, the probability of excluding the second type of resource at block 840 may be lower than 100%. It means that less resources may be excluded from the initial set of candidate resources. Thus, more candidate resources may be provided to high layer for sidelink transmission.

It shall be appreciated that, although presented herein as being performed serially, at least a portion of the actions of the method 800B may be performed contemporaneously or in a different order than as presented in Fig. 8B. For example, the action at block 830 may be performed after the action at block 835. Alternatively, the actions at

blocks

830 and 835 may be performed contemporaneously. The scope of the present disclosure is not limited in this regard.

In some embodiments, the terminal device 110 may determine both the first factor and the second factor. The terminal device 110 may exclude the first type of resource from the initial set of candidate resources by the first probability and the second type of resource from the initial set of candidate resources by the second probability. The first probability may be determined based on the first factor. The second probability may be determined based on the second factor. This will be described with reference to Fig. 8C.

Fig. 8C illustrates a flowchart of an example method 800C in accordance with some embodiments of the present disclosure. The method 800C may be considered as an example implementation of the method 700. In some embodiments, the method 800C can be implemented at a terminal device, such as one of the terminal device 110, the terminal device 120 and the terminal device 130 as shown in Fig. 1. For the purpose of discussion, the method 800C will be described with reference to Fig. 1 as performed by the terminal device 110 without loss of generality.

At block 850, the terminal device 110 determines the first factor and the second factor.

At block 855, the terminal device 110 identifies the first type of resource reserved with period and the second type of resource reserved with time offset.

At block 860, the terminal device 110 excludes the first type of resource from the initial set of candidate resources by the first probability and excludes the second type of resource from the initial set of candidate resources by the second probability. The first probability is determined based on the first factor. The second probability is determined based on the second factor.

At block 865, the terminal device 110 determines the first set of candidate resources.

It will be understood that the probability of excluding the resource in the legacy mode 2 procedure is 100%. However, the probability of excluding the first type of resource at block 860 may be lower than 100%and the probability of excluding the second type of resource at block 860 may be lower than 100%. It means that less resources may be excluded from the initial set of candidate resources. Thus, more candidate resources may be provided to high layer for sidelink transmission.

It shall be appreciated that, although presented herein as being performed serially, at least a portion of the actions of the method 800C may be performed contemporaneously or in a different order than as presented in Fig. 8C. For example, the action at block 850 may be performed after the action at block 855. Alternatively, the actions at

blocks

850 and 855 may be performed contemporaneously. The scope of the present disclosure is not limited in this regard.

In some embodiments, the terminal device 110 may determine a second threshold of RSRP based on the third factor. In such embodiments, the terminal device 110 may determine the second threshold as the first threshold multiplied by the third factor.

For example, the terminal device 110 may determine the second threshold base on the following:

Where

represents the second threshold of RSRP,

represents the first threshold of RSRP and γ represents the third factor and 1≤γ. In such example, the second threshold

may be an RSRP threshold for SL-U, the first threshold may be an RSRP threshold

for the legacy mode 2 procedure.

In some other embodiments, the terminal device 110 may determine the second threshold of RSRP based on the fourth factor. In such embodiments, the terminal device 110 may determine the second threshold as the first threshold plus the fourth factor.

Where Δ represents the fourth factor and may be an integer.

Upon determining the second threshold of RSRP, the terminal device 110 may exclude the reserved resource from the initial set of candidate resources based on the second threshold. This will be described with reference to Fig. 8D.

Fig. 8D illustrates a flowchart of an example method 800D in accordance with some embodiments of the present disclosure. The method 800D may be considered as an example implementation of the method 700. In some embodiments, the method 800D can be implemented at a terminal device, such as one of the terminal device 110, the terminal device 120 and the terminal device 130 as shown in Fig. 1. For the purpose of discussion, the method 800D will be described with reference to Fig. 1 as performed by the terminal device 110 without loss of generality.

At block 870, the terminal device 110 determines the third factor or the fourth factor.

At block 875, the terminal device 110 identifies the reserved resource for sidelink communication. The reserved resource may include the first type of resource reserved with period and/or the second type of resource reserved with time offset.

At block 880, the terminal device 110 excludes the reserved resource from the initial set of candidate resources based on the second threshold of RSRP. The second threshold of RSRP may be determined based on the third factor or the fourth factor.

At block 885, the terminal device 110 determines the first set of candidate resources.

It will be understood that the second threshold of RSRP may be larger than the first threshold of RSRP for the legacy mode 2 procedure. It means that less resources may be excluded from the initial set of candidate resources. Thus, more candidate resources may be provided to high layer for sidelink transmission.

It shall be appreciated that, although presented herein as being performed serially, at least a portion of the actions of the method 800D may be performed contemporaneously or in a different order than as presented in Fig. 8D. For example, the action at block 870 may be performed after the action at block 875. Alternatively, the actions at

blocks

870 and 875 may be performed contemporaneously. The scope of the present disclosure is not limited in this regard.

In some embodiments, the terminal device 110 may determine the at least one factor based on at least one of the following:

● a Channel Occupancy Ratio (CR) of sidelink,

● a Channel Busy Ratio (CBR) of sidelink,

● a sensing duration of a channel access (CA) procedure,

● a type of the CA procedure,

● a Hybrid Automatic Repeat Request (HARQ) feedback of sidelink,

● a pre-definition,

● a pre-configuration, or

● a configuration.

In embodiments where the terminal device 110 determines the at least one factor based on CBR of sidelink, mapping relationship between the at least one factor and CBR may be pre-defined, configured or pre-configured. The mapping relationship may be independent mapping relationship between each factor and CBR. Alternatively, the mapping relationship may be the combined mapping relationship between two or more factors and CBR.

As CBR presents the channel status to some extent, determining the at least one factor based on CBR of sidelink can provide a reasonable value for the factor, and further improve the resource selection for SL-U.

Table 1 shows an example of the mapping relationship between the first factor α and CBR represented by r1. The mapping relationship may be predefined in SL-U communication system. According to the mapping relationship, the terminal device 110 may determine the first factor α based on the CBR measurement.

Table 1

CBR (r1)	α
r1≤0.1	a0
0.1<r1≤0.2	a1

0.2<r1≤0.3	a2
……	……
0.9<r1≤1	a9

Table 2 shows an example of the mapping relationship between the first factor α, the second factor β, the third factor γ and CBR represented by r1. The mapping relationship may be configured by a network node through RRC signaling. According to the configuration, the terminal device 110 may determine the factors based on the CBR measurement.

Table 2

CBR (r1)	α	β	γ
r1≤0.1	a0	b0	c0
0.1<r1≤0.2	a1	b1	c1
0.2<r1≤0.3	a2	b2	c2
……	……	……	……
0.9<r1≤1	a9	b9	c9

In embodiments where the terminal device 110 determines the at least one factor based on CR of sidelink, mapping relationship between the at least one factor and CR may be pre-defined, configured or pre-configured. The mapping relationship may be independent mapping relationship between each factor and CR. Alternatively, the mapping relationship may be the combined mapping relationship between two or more factors and CR.

As CR presents the channel status to some extent, determining the at least one factor based on CR of sidelink can provide a reasonable value for the factor, and further improve the resource selection for SL-U.

Table 3 shows an example of the mapping relationship between the fourth factor Δ and CR represented by r2. The mapping relationship may be pre-configured in SL-U communication system. According to the mapping relation, the terminal device 110 may determine the fourth factor Δ based on the CR of the terminal device 110 itself.

Table 3

CR (r2)	Δ (dB)
r2≤0.1	P0
0.1<r2≤0.2	P1
0.2<r2≤0.3	P2
……	……
0.9<r2≤1	P9

In embodiments where the terminal device 110 determines the at least one factor based on CR and CBR of sidelink, a combined mapping relationship among the at least one factor, CR and CBR may be pre-defined, configured or pre-configured.

Table 4 shows an example of the combined mapping relationship among the first factor α, the second factor β, the fourth factor Δ, CBR represented by r and CR represented by r2. The combined mapping relationship is configured by a network node through RRC signaling. According to the configuration, the terminal device 110 may determine the factors based on the CBR measurements and CR of the terminal device.

Table 4

It should be understood that the CBR or CR in Tables 1 to 4 are described by way of example, elipses in Tables 1 to 4 mean that other CBR or CR may be also applied to the present disclosure and are omitted for brevity.

In embodiments the terminal device 110 determines the at least one factor based on the type of the CA procedure, the type of the CA procedure may comprise at least one of the following: a type 1 CA procedure, a type 2A CA procedure, a type 2B CA procedure, or a type 2C CA procedure.

For different types of CA procedure, the probability of the reserved resources can be used may be different. Therefore, determining the at least one factor according to the type of CA procedure can provide suitable modification for the legacy mode 2 procedure.

In an example, the first factor α and the fourth factor Δ may be determined according to the type of CA procedure used by the terminal device 110, as shown in Table 5.

Table 5

Type of CA procedure	α	Δ (dB)
Type 1	a0	P0
Type 2A	a1	P1
Type 2B	a2	P2

Type 2C

a3

P3

In embodiments the terminal device 110 determines the at least one factor based on the sensing duration of the last type 1 CA procedure performed by the terminal device 110, the mapping relationship between the at least one factor and the sensing duration represented by l may be pre-defined, configured or pre-configured. The mapping relationship may be independent mapping relationship between each factor and the sensing duration. Alternatively, the mapping relationship may be the combined mapping relationship between two or more factors and the sensing duration.

The sensing duration of the last type 1 CA procedure before trigger of the sensing and resource selection procedure presents the channel status recently. Thus, determining the at least one factor according to the sensing duration can provide a reasonable value for the factors, and further improve the resource selection for SL-U.

Table 6 shows an example of the combined mapping relationship among the first factor α, the second factor β, the third factor γ, and the sensing duration represented by l.

Table 6

It should be understood that the sensing durations in Table 6 are described by way of example, elipses in Table 6 mean that other sensing durations may be also applied to the present disclosure and are omitted for brevity.

In some embodiments, the sensing duration of the CA procedure comprises at least one of the following: a sensing duration of a last successful type 1 CA procedure performed by the terminal device 110, or a sensing duration of a last type 1 CA procedure performed by the terminal device 110. This will be described with reference to Fig. 9.

Fig. 9 illustrates an example of a sensing duration of the last type 1 CA procedure in accordance with some embodiments of the present disclosure. As shown, within a time duration 910, the terminal device 110 performs a type 1 CA procedure and succeeds in occupying the channel. In turn, the terminal device 110 transmits a sidelink signal within a time duration 920. Within a time duration 930, the terminal device 110 performs a type 1 CA procedure and fails to occupy the channel. At time 940, the terminal device 110 triggers a sensing and resource selection procedure according to the present disclosure.

In such example, the type 1 CA procedure performed within the time duration 910 is the last successful type 1 CA procedure performed by the terminal device 110, and the type 1 CA procedure performed within the time duration 930 is the last type 1 CA procedure performed by the terminal device 110. The terminal device 110 may determine the at least one factor based on a sensing duration of the last successful type 1 CA procedure performed by the terminal device 110 within the time duration 910. Alternatively, the terminal device 110 may determine the at least one factor based on a sensing duration of the last type 1 CA procedure performed by the terminal device 110 within the time duration 930.

In some embodiments, the terminal device 110 may determine the sensing duration as a contention window of the CA procedure. For example, the terminal device 110 may determine the sensing duration based on the following:

l= CW _p

where l represents the sensing duration and CW _p represents the contention window of the CA procedure for priority p.

In some embodiments, the terminal device 110 may determine the sensing duration as a random number uniformly distributed between zero and the contention window CW _p of the CA procedure. For example, the terminal device 110 may determine the sensing duration based on the following:

l=N _init

where l represents the sensing duration and N _init represents the random number.

In some embodiments, the terminal device 110 may determine the sensing duration as a time duration which is determined based on the random number and at least one additional defer duration within the CA procedure. For example, the terminal device 110 may determine the sensing duration based on the following:

l= (N _init+T _d)

where l represents the sensing duration, N _init represents the random number, and T _d represents an additional defer duration within a CA procedure.

In some embodiments, there are more than one T _d within a CA procedure. In such embodiments, the sensing duration may equal to all the T _d plus N _init, i.e.,

where i represents an index of the i-th T _d;

In some embodiments, the terminal device 110 may determine the at least one factor as a function of the sensing duration. In this way, no signaling indication or configuration is needed, and signaling overhead may be reduced.

In some embodiments, the terminal device 110 may determine the first factor based on the sensing duration, a minimum value of the first factor and a maximum value of the sensing duration. At least one of the maximum value of the sensing duration and the minimum value of the first factor may be pre-defined, or pre-configured or configured by a control node device. For example, the terminal device 110 may determine the first factor based on the following:

α=a _min· (l _max/l)

where α represents the first factor, l _max represents the maximum value of the sensing duration l, a _min represents the minimum value of α. l _max may be pre-configured or configured by a control node device, or l _max=CW _max, p, where CW _max, p represents the maximum value of the contention window for priority p. a _min may be pre-configured or configured by a control node device or set to a fixed value.

In some embodiments, the terminal device 110 may determine the second factor based on the sensing duration, a minimum value of the second factor and the maximum value of the sensing duration. At least one of the maximum value of the sensing duration and the minimum value of the second factor may be pre-defined, or pre-configured or configured by a control node device. For example, the terminal device 110 may determine the second factor based on the following:

β=β _min· (l _max/l)

where β represents the second factor, and β _min represents the minimum value of β.

In some embodiments, the terminal device 110 may determine the third factor based on the sensing duration, a maximum value of the third factor and the maximum value of the sensing duration. At least one of the maximum value of the third factor and the maximum value of the sensing duration may be pre-defined, or pre-configured or configured by a control node device. For example, the terminal device 110 may determine the third factor based on the following:

γ=γ _MAX· (l/l _max)

where γ represents the third factor, γ _MAX represents the maximum value of γ. γ _MAX may be pre-configured or configured by a control node device or set to a fixed value.

In some embodiments, the terminal device 110 may determine the fourth factor based on the sensing duration, a maximum value of the fourth factor and the maximum value of the sensing duration. At least one of the maximum value of the fourth factor and the maximum value of the sensing duration may be pre-defined, or pre-configured or configured by a control node device. For example, the terminal device 110 may determine the fourth factor based on the following:

Δ =Δ _MAX· (l/l _max)

where Δ represents the fourth factor, Δ _MAX represents the maximum value of Δ. Δ _MAX may be pre-configured or configured by a control node device or set to a fixed value.

In embodiments where the terminal device 110 determines the at least one factor based on the HARQ feedback of sidelink, the HARQ feedback comprises at least one of the following: a HARQ feedback detected by the terminal device 110 on PSFCH, a HARQ feedback detected by the terminal device 110 in SCI, a HARQ feedback associated with sidelink unicast, a HARQ feedback associated with sidelink groupcast, or a HARQ feedback associated with sidelink broadcast.

For example, according to the system pre-configuration, the terminal device 110 determines the first factor α and the fourth factor Δ for a sensing and resource selection procedure based on the sidelink ACK/NACK received on PSFCH. The sensing and resource selection procedure aims to select candidate resources for groupcast, and the factors should be determined according to the ACK/NACK detected for the same groupcast transmission.

As the HARQ feedback of sidelink presents the channel status to some extent, determining the at least one factor based on the HARQ feedback can provide a reasonable value for the factor, and further improve the resource selection for SL-U.

In embodiments where the terminal device 110 determines the at least one factor based on the HARQ feedback of sidelink, the terminal device 110 may determine the at least one factor based on at least one of the following: the number of positive acknowledges (ACKs) detected by the terminal device 110, the number of negative acknowledges (NACKs) detected by the terminal device 110, a ratio of the number of the ACKs detected by the terminal device 110 to a total number of resources for carrying sidelink HARQ feedback information, or a ratio of the number of the NACKs detected by the terminal device 110 to a total number of resources for carrying sidelink HARQ feedback information.

In some embodiments, at least one of the number and the ratio may be predefined, configured or pre-configured. For example, according to the system predefinition, the relationship between the ratio of received ACK and factors is pre-configured as following:

Table 7

In embodiments where the terminal device 110 determines the at least one factor based on the pre-configuration or configuration, the pre-configuration or configuration may be indicated by a control node device through high layer signaling. In this way, no or less signaling overhead is required.

In some embodiments, the terminal device 110 may determine the first set of candidate resources based on the at least one factor in response to a first indicator which indicates that the determination of the at least one factor is enabled.

In some embodiments, the first indicator is indicated by a control node device.

In some embodiments, the terminal device 110 may determine the first set of candidate resources based on the at least one factor in response to at least one of the following:

● a CR of sidelink exceeds a first ratio,

● a CBR of sidelink exceeds a second ratio,

● a length of a sensing duration of a CA procedure exceeds a third threshold,

● a given type of the CA procedure to be performed by the terminal device,

● the number of ACKs detected by the terminal device exceeds a fourth threshold,

● the number of NACKs detected by the terminal device exceeds a fifth threshold,

● a ratio of the number of the ACKs detected by the terminal device to a total number of resources for carrying sidelink HARQ feedback information exceeds a sixth threshold,

● a ratio of the number of the NACKs detected by the terminal device to a total number of resources for carrying sidelink HARQ feedback information exceeds a seventh threshold,

● the first threshold of RSRP is increased by a power offset which exceeds an eighth threshold, or

● the number of candidate resources remaining in the set of candidate resource is smaller than a ninth threshold.

In some embodiments, at least one of the following is pre-defined, or pre-configured or configured by a control node device: the first ratio, the second ratio, the third threshold, the fourth threshold, the fifth threshold, the sixth threshold, the seventh threshold, the eighth threshold, or the ninth threshold.

Fig. 10 illustrates a flowchart of an example method 1000 in accordance with some embodiments of the present disclosure. The method 1000 may be considered as an example implementation of the method 700. In some embodiments, the method 1000 can be implemented at a terminal device, such as one of the terminal device 110, the terminal device 120 and the terminal device 130 as shown in Fig. 1. For the purpose of discussion, the method 1000 will be described with reference to Fig. 1 as performed by the terminal device 110 without loss of generality.

At block 1010, the terminal device 110 starts the legacy mode 2 sensing and resource selection procedure.

At block 1020, the terminal device 110 determines the candidate resource set.

At block 1030, the terminal device 110 determines whether the number of candidate resources remaining in the first set of candidate resources is smaller than the ninth threshold.

If the number of candidate resources remaining in the first set of candidate resources is smaller than the ninth threshold, a block 1040, the terminal device 110 triggers to start the sensing and resource selection procedure according to the present disclosure. For example, the terminal device 110 may trigger to start any of the sensing and resource selection procedures described with reference to Figs. 7, 8A, 8B, 8C and 8D.

At block 1050, the terminal device 110 excludes the reserved resource based on at least one factor according to the present disclosure.

If the number of candidate resources remaining in the first set of candidate resources is not smaller than the ninth threshold, at block 1060, the terminal device 110 determines the candidate resource set and reports it to high layer.

Fig. 11 illustrates a flowchart of an example method 1100 in accordance with some embodiments of the present disclosure. The method 1100 may be considered as an example implementation of the method 700. In some embodiments, the method 1100 can be implemented at a terminal device, such as one of the terminal device 110, the terminal device 120 and the terminal device 130 as shown in Fig. 1. For the purpose of discussion, the method 1100 will be described with reference to Fig. 1 as performed by the terminal device 110 without loss of generality.

At block 1110, the terminal device 110 starts the legacy mode 2 sensing and resource selection procedure.

At block 1120, the terminal device 110 determines the first set A of candidate resources.

At block 1130, the terminal device 110 determines whether the first threshold of RSRP is increased by a power offset which exceeds the eighth threshold.

If the first threshold of RSRP is increased by a power offset which exceeds the eighth threshold, a block 1140, the terminal device 110 triggers to start the sensing and resource selection procedure according to the present disclosure. For example, the terminal device 110 may trigger to start any of the sensing and resource selection procedures described with reference to Figs. 7, 8A, 8B, 8C and 8D.

At block 1150, the terminal device 110 excludes the reserved resource based on at least one factor according to the present disclosure so as to determine a first set B of candidate resources.

At block 1160, the terminal device 110 determines the first set B of candidate resources and reports it to high layer.

If the first threshold of RSRP is not increased by a power offset which exceeds the eighth threshold, a block 1170, the terminal device 110 reports the first set A of candidate resources to high layer.

Fig. 12 is a simplified block diagram of a device 1200 that is suitable for implementing some embodiments of the present disclosure. The device 1200 can be considered as a further example embodiment of the terminal device 110 as shown in Fig. 1. Accordingly, the device 1200 can be implemented at or as at least a part of the terminal device 110.

As shown, the device 1200 includes a processor 1210, a memory 1220 coupled to the processor 1210, a suitable transmitter (TX) and receiver (RX) 1240 coupled to the processor 1210, and a communication interface coupled to the TX/RX 1240. The memory 1220 stores at least a part of a program 1230. The TX/RX 1240 is for bidirectional communications. The TX/RX 1240 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2 interface for bidirectional communications between gNBs or eNBs, S1 interface for communication between a Mobility Management Entity (MME) /Serving Gateway (S-GW) and the gNB or eNB, Un interface for communication between the gNB or eNB and a relay node (RN) , or Uu interface for communication between the gNB or eNB and a terminal device.

The program 1230 is assumed to include program instructions that, when executed by the associated processor 1210, enable the device 1200 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to Figs. 5 to 14. The embodiments herein may be implemented by computer software executable by the processor 1210 of the device 1200, or by hardware, or by a combination of software and hardware. The processor 1210 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 1210 and memory 1220 may form processing means 1250 adapted to implement various embodiments of the present disclosure.

The memory 1220 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 1220 is shown in the device 1200, there may be several physically distinct memory modules in the device 1200. The processor 1210 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1200 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

The components included in the apparatuses and/or devices of the present disclosure may be implemented in various manners, including software, hardware, firmware, or any combination thereof. In one embodiment, one or more units may be implemented using software and/or firmware, for example, machine-executable instructions stored on the storage medium. In addition to or instead of machine-executable instructions, parts or all of the units in the apparatuses and/or devices may be implemented, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs) , Application-specific Integrated Circuits (ASICs) , Application-specific Standard Products (ASSPs) , System-on-a-chip systems (SOCs) , Complex Programmable Logic Devices (CPLDs) , and the like.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to any of Figs. 1 to 11. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific embodiment details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A method for communications, comprising:

determining, at a terminal device, at least one factor for sidelink communication; and

determining a first set of candidate resources by excluding a reserved resource from an initial set of candidate resources based on the at least one factor;

the at least one factor comprising at least one of the following:

a first factor associated with a first type of resource reserved with period,

a second factor associated with a second type of resource reserved with time offset,

a third factor associated with a first threshold of Reference Signal Receiving Power (RSRP) , or

a fourth factor associated with the first threshold.
The method of claim 1, further comprising:

reporting the first set of candidate resources to high layer of the terminal device.
The method of claim 1, wherein excluding the reserved resource from the initial set of candidate resources based on the at least one factor comprises at least one of the following:

excluding the first type of resource from the initial set of candidate resources by a first probability, the first probability being determined based on the first factor, or

excluding the second type of resource from the initial set of candidate resources by a second probability, the second probability being determined based on the second factor.
The method of claim 1, wherein excluding the reserved resource from the initial set of candidate resources based on the at least one factor comprises:

determining a second threshold of RSRP based on the third factor or the fourth factor; and

excluding the reserved resource from the initial set of candidate resources based on the second threshold.
The method of claim 4, wherein determining the second threshold of RSRP based on the third factor or the fourth factor comprises:

determining the second threshold as the first threshold multiplied by the third factor; or

determining the second threshold as the first threshold plus the fourth factor.
The method of claim 1, wherein determining the at least one factor comprises:

determining the at least one factor based on at least one of the following:

a Channel Occupancy Ratio (CR) of sidelink,

a Channel Busy Ratio (CBR) of sidelink,

a sensing duration of a channel access (CA) procedure,

a type of the CA procedure,

a Hybrid Automatic Repeat Request (HARQ) feedback of sidelink,

a pre-definition,

a pre-configuration, or

a configuration.
The method of claim 6, wherein the type of the CA procedure comprises at least one of the following:

a type 1 CA procedure,

a type 2A CA procedure,

a type 2B CA procedure, or

a type 2C CA procedure.
The method of claim 6, wherein determining the at least one factor based on the sensing duration comprises at least one of the following:

determining the first factor based on the sensing duration, a minimum value of the first factor and a maximum value of the sensing duration;

determining the second factor based on the sensing duration, a minimum value of the second factor and the maximum value of the sensing duration;

determining the third factor based on the sensing duration, a maximum value of the third factor and the maximum value of the sensing duration; or

determining the fourth factor based on the sensing duration, a maximum value of the fourth factor and the maximum value of the sensing duration.
The method of claim 8, wherein at least one of the following is pre-defined, or pre-configured or configured by a control node device:

the maximum value of the sensing duration;

the minimum value of the first factor;

the minimum value of the second factor;

the maximum value of the third factor; or

the maximum value of the fourth factor.
The method of claim 6, wherein the sensing duration of a CA procedure comprises at least one of the following:

a sensing duration of a last successful type 1 CA procedure performed by the terminal device, or

a sensing duration of a last type 1 CA procedure performed by the terminal device.
The method of claim 6, wherein determining the at least one factor based on the sensing duration of a CA procedure comprises:

determining the sensing duration as at least one of the following:

a random number uniformly distributed between zero and a contention window of the CA procedure,

a time duration which is determined based on the random number and at least one additional defer duration within the CA procedure, or

a contention window of the CA procedure.
The method of claim 6, wherein the HARQ feedback comprises at least one of the following:

a HARQ feedback detected by the terminal device on Physical Sidelink Feedback Channel,

a HARQ feedback detected by the terminal device in Sidelink Control Information,

a HARQ feedback associated with sidelink unicast,

a HARQ feedback associated with sidelink groupcast, or

a HARQ feedback associated with sidelink broadcast.
The method of claim 6, wherein determining the at least one factor based on the HARQ feedback comprises:

determining the at least one factor based on at least one of the following:

the number of positive acknowledges (ACKs) detected by the terminal device,

the number of negative acknowledges (NACKs) detected by the terminal device,

a ratio of the number of the ACKs detected by the terminal device to a total number of resources for carrying sidelink HARQ feedback information, or

a ratio of the number of the NACKs detected by the terminal device to a total number of resources for carrying sidelink HARQ feedback information.
The method of claim 6, wherein the pre-configuration or configuration is indicated by a control node device.
The method of claim 1, wherein determining the first set of candidate resources comprises:

determining the first set of candidate resources based on the at least one factor in response to at least one of the following:

a first indicator which indicates that the determination of the at least one factor is enabled,

a Channel Occupancy Ratio (CR) of sidelink exceeds a first ratio,

a Channel Busy Ratio (CBR) of sidelink exceeds a second ratio,

a length of a sensing duration of a channel access (CA) procedure exceeds a third threshold,

a given type of the CA procedure to be performed by the terminal device,

the number of positive acknowledges (ACKs) detected by the terminal device exceeds a fourth threshold,

the number of negative acknowledges (NACKs) detected by the terminal device exceeds a fifth threshold,

a ratio of the number of the ACKs detected by the terminal device to a total number of resources for carrying sidelink HARQ feedback information exceeds a sixth threshold,

a ratio of the number of the NACKs detected by the terminal device to a total number of resources for carrying sidelink HARQ feedback information exceeds a seventh threshold,

the first threshold of RSRP is increased by a power offset which exceeds an eighth threshold, or

the number of candidate resources remaining in the first set of candidate resources is smaller than a ninth threshold.
The method of claim 15, wherein the first indicator is indicated by a control node device.
The method of claim 15, wherein at least one of the following is pre-defined, or pre-configured or configured by a control node device:

the first ratio,

the second ratio,

the third threshold,

the fourth threshold,

the fifth threshold,

the sixth threshold,

the seventh threshold,

the eighth threshold, or

the ninth threshold.
A terminal device, comprising:

a processor; and

a memory coupled to the processor and storing instructions thereon, the instructions, when executed by the processor, causing the terminal device to perform the method according to any of claims 1-17.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor of a device, causing the device to carry out the method according to any of claims 1-17.